Only head coach Mike Zimmer's hiring has been officially announced by the Minnesota Vikings, but his staff is starting to take shape.

The Vikings have reportedly added Jerry Gray as a defensive backs coach per FOX Sports, replacing Joe Woods as one of many of former coach Leslie Frazier's assistants who will not stick around. Woods, who had been with the Vikings since Brad Childress was hired in 2006, was let go this week, per ESPN.com.

Gray, 51, is tasked with turning around one of the worst secondaries in NFL history as the Vikings allowed 37 passing touchdowns, tying the most since the NFL-AFL merger in 1970.

Gray spent the last three seasons as the Tennessee Titans defensive coordinator, most recently leading the 2013 Titans that finished 14th in yards per game (337.9) and 16th in points per game (23.8) allowed. He will join the staff of George Edwards, who reportedly was added to Zimmer's staff last week.

Edwards replaces former defensive coordinator Alan Williams, who reportedly has landed with the Detroit Lions as a defensive backs coach, per the St. Paul Pioneer Press.

Four Vikings assistants have the best chance of landing an interview to stay on with Zimmer, per ESPN.com. Receivers coach George Stewart, linebackers coach and former DC Fred Pagac, special teams coach Mike Priefer and offensive line coach Jeff Davidson are the top candidates to stay.

Former offensive coordinator Bill Musgrave has signed on with the Philadelphia Eagles as their quarterbacks coach and former Vikings QB coach Craig Johnson was announced as the New York Giants' running back coach on Wednesday.